AN ABSTRACT OF THE THESIS OF Michael Curtis Hagood for the Master of Science in Geology presented February 21, 1985. Title: Structure-and Evolution of the Horse Heaven Hills in South-Central Washington. APPROVED BY MEMBERS OF THE THESIS COMMITTEE: Marvin H. Beeson, Chairman Michael L. Cummings Gilbert T. Benson Stephen P. Reidel The Horse Heaven Hills uplift in south-central Washington con- sists of distinct northwest and northeast trends which merge in the lower Yakima Valley. The northwest trend is adjacent to and parallels the Rattlesnake-Wallula alignment (RAW; a part of the Olympic-Wallowa lineament). The northwest trend and northeast trend consist of aligned or en echelon anticlines and monoclines whose axes are gener- ally oriented in the direction of the trend. At the intersection, La 2 folds in the northeast trend plunge onto and are terminated by folds of the northwest trend. The crest of the Horse Heaven Hills uplift within both trends is composed of a series of asymmetric, north vergent, eroded, usually double-hinged anticlines or monoclines. Some of these "major" anti- clines and monoclines are paralleled to the immediate north by lower- relief anticlines or monoclines. All anticlines approach monoclines in geometry and often change to a monoclinal geometry along their length. In both trends, reverse faults commonly parallel the axes of folds within the tightly folded hinge zones. Tear faults cut across the northern limbs of the anticlines and monoclines and are coincident with marked changes in the wavelength of a fold or a change in the trend of a fold. Layer-parallel faults commonly exist along steeply- dipping stratigraphic contacts or zones of preferred weakness in intraflow structures. Most of these faults appear to reflect strain from folding. Isopach maps of Columbia River basalt (CRB) flows/Ellensburg Formation nterbeds and paleodrainage maps of the ancestral Columbia River system indicate that deformation occurred simultaneously and coincident with both trends of the Horse Heaven Hills uplift, the lower Yakima Valley syncline, the Piening syncline (within the Horse Heaven Plateau), and the Hog Ranch-Naneum Ridge anticline (within the lower Yakima Valley) since at least Roza time. Data are not available for determining the timing and location of deformation prior to Roza time, nor does the geologic record allow for a detailed description of 3 present the observed except that CR6 time, after history after uplift developed the growth Heaven Hills the Horse relief along structural m.y.B.P.). time (10.5 the lower Mountain uplift and Elephant Heaven Hills the Horse approximately between of less than Relief at a rate developed rate of syncline time (combined Yakima Valley Mountains and Saddle decrease during Wanapum appear to 70 mm.y., Growth rates and subsidence). rates extrapolated vertical uplift time. Growth Mountains since and Saddle developed during Wanapum relief the cumulative at a approximate developed the present that folds to possibility the the data from time indicating However, Wanapum to the present. CRB CRB time rates in post rate since of growth uniform variability preclude the study do not this directly models which time. that tectonic study suggest Hills uplift from this Heaven Data of the Horse to the origin or near- pertain of monoclinal or indirectly (1) the predominance northwest by: both the be constrained faults along might and reverse geometries suggest clockwise fold data which monoclinal preliminary along both trends; (2) (3) folds and northeast of both trends; along folds (at least occurred similar rates rotation has and at simultaneously the north- developing folds along trends were time); (4) Mountains related to and Saddle genetically during Wanapum uplift are Heaven Hills the RAW; of the Horse folds along west trend some with at least the north-northwest- formed simultaneously with and simultaneously was developing as other Yakima (5) the uplift as well Ridge anticline of both Ranch-Naneum that folds trending Hog is proposed time. It at least CRB folds during 4 trends of the Horse Heaven Hills uplift were generated by the same tectonic processes. , . STRUCTURE AND EVOLUTION OF THE HORSE HEAVEN HILLS IN SOUTH-CENTRAL WASHINGTON by ,~ . , . ..t- e.. .- .- ~ - I & . MICHAEL CURTIS HAGOOD A thesis submitted n partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in GEOLOGY Portland State University 1985 TO '.t OFFICE OF GRADUATE STUDIES AND RESEARCH: The members of the Committee approve the thesis of Michael Curtis Hagood presented February 21, 1985. Marvin H. Beeson, Chairman Michael L. Cummings Gilbert T. Benson Stephen P. Reidel APPROVED: Paul E. Hammond, Head, Department of Geology Jim F. Heath, Dean of Graduate Studies and Research I ACKNOWLEDGEMENTS I would like to thank Dr. Stephen Reldel for introducing me to the many geologic aspects of the Columbia Plateau. His enthusiastic support, insight, and guidance were drawn upon frequently. Many discussions with Stephen Reidel, Terry Tolan, and Karl Fecht generated several ideas that were incorporated into this study. These three also provided very thorough reviews of the thesis which greatly improved it. As my thesis advisor, Dr. Marvin Beeson provided timely advice, support, and beneficial reviews of the thesis, and deserves my sincere thanks. I would also like to thank Drs. Michael Cummings and Tom Benson for their constructive reviews of the thesis. This study was funded by a grant from the Northwest College and University Association for Science (NORCUS), with additional support from Rockwell Hanford Operations. I wish to express my thanks to Dr. Brian Valett of NORCUS for his assistance. I would like to thank the staff and management of Rockwell Hanford Operations for their support of this study. Drs. Stephen Reidel, Ann Tallman, and Terry Tolan took time out from their busy schedules to make sure support for various aspects of the study were there. Bill Crowely aided immensely in the drafting of many of the figures and maps. Dale Landon provided some unpublished mapping, chemical analyses, and an initial orientation to the study area. Don Saul, Donna Starr, and Dave Thiede patiently instructed me in the use 5 iv of the computers and computer programs. Steve Strait provided helpful information and support for borehole geophysical logging. Several other people and organizations contributed technical support to the study. B1ll Myer of the Department of Ecology first Introduced me to the utility of borehole geophysical logs, and freely and enthusiastically discussed aspects of the area geology. In addi- tion, discussions with Frank Packard of the U.S. Geological Survey have been most beneficial. The U.S. Geological Survey in Tacoma, Washington allowed the use of several unpublished borehole geophysical logs. Washington State University College of Engineering provided me with borehole geophysical logs. Randy Brown of Richland, Washington provided useful information for interpreting driller's logs. Drs. Bob Simpson and Ray Wells allowed me the use of their unpublished paleomagnetic data. Jim, Dan, and Christine Dilts provided me with drill cuttings from the Moon 1 well. I would like to thank landowners Pete Sharpe, Milo Bauder, Bill Phelps, and Paul Drake for allowing me access to their property. I also wish to say thank you to my parents, Mel and Pat Hagood, for their support during this study. Lastly, but of no less importance, I wish to thank my wife, Mary Jean, for her patience and understanding through the duration of this study; and for putting up with the lost weekends and evenings, as well as my absences during field seasons. I TABLE OF CONTENTS PAGE ACKNOWLEDGEMENTS . * * * . * . * . iii LIST OF TABLES * . * * . * * * 9 * 9 * * * * * * 9 9 viii LIST OF FIGURES . *. x * . S * *- 0 *, ' '-1 , ' -F I-, , . INTRODUCTION . 1 L - Purpose . * . 1 Regional Geologic Setting . 4 Location and Physical Description . * . 9 * * * . 9 . 9 5 Methodology . * . S 9 * 6 * . Previous Work . 7 STRATIGRAPHY . 9 Grande Ronde Basalt . .. .. 9 Wanapum Basalt . 11 Frenchman Springs Member. 15 Roza Member .. .. ... ... 17 Priest Rapids Member. .. 18 Saddle Mountains Basalt . ........ ........ 19 Umatilla Member . 19 Esquatzel Member .................... 22 Pomona Member . .. .. ... .. ....... 22 Elephant Mountain Member ................ 25 Ice Harbor Member . .. .. 26 vi Ellensburg Formation . * * a * & 27 Squaw Creek Member. * . 29 Quincy Interbed . * * * * 29 Byron Interbed . * . 30 Mabton Interbed . 30 Cold Creek Interbed . 32 Selah Interbed . 32 Rattlesnake Ridge Interbed. * . * . S 36 Levey Interbed . * * * *. 38 Snipes Mountain Conglomerate. 38 McBee Conglomerate. 40 Undifferentiated Ellensburg Formation Sediments 42. STRUCTURE . S * 0S S S S * *. * * ** * * 43 Structure of the Immediate Area * a O * * 43 Horse Heaven Hills Uplift . * * * * O * * * S * * 0 * O * 47 - Byron Segment . 50 Gibbon Segment 54 Chandler Segment . S S *~ * ...............* * * S * S 58 Webber Segment . 61 Kiona Segment . S * * * S * . * . * * . * * * 65 Junction Segment 68 TIMING AND LOCATION OF DEFORMATION * . * 71 Isopach Study . * * . O* * * * * * 72 Paleodrainage . .. *. * * * . * 90 GROWTH RATES . 101 CONSTRAINTS ON TECTONIC MODELS FOR THE DEVELOPMENT OF THE HORSE HEAVEN HILLS UPLIFT . .. * * * * * . 107 East-West-Trending Folds . .. 109 Northwest-Trending Folds . .... 111 Constraints . 112 I vii CONCLUSIONS . 116 REFERENCES CITED . 121 APPENDIX A. Chemical Analyses . 133 B. Borehole Logs . 138 8orehol~e Geophysical Logs . 138 Driller's